Wolfgang Grandegger wrote:
> Gilles Chanteperdrix wrote:
> > Gilles Chanteperdrix wrote:
> > > Wolfgang Grandegger wrote:
> > > > Hi Gilles,
> > > >
> > > > Gilles Chanteperdrix wrote:
> > > > > On Dec 6, 2007 3:05 PM, Wolfgang Grandegger <[EMAIL PROTECTED]>
> > wrote:
> > > > >> Gilles Chanteperdrix wrote:
> > > > >>> On Dec 6, 2007 2:28 PM, Gilles Chanteperdrix
> > > > >>> <[EMAIL PROTECTED]> wrote:
> > > > >>>> On Dec 6, 2007 2:24 PM, Wolfgang Grandegger <[EMAIL PROTECTED]>
> > wrote:
> > > > >>>>> Gilles Chanteperdrix wrote:
> > > > >>>>>> On Dec 6, 2007 1:31 PM, Wolfgang Grandegger <[EMAIL
> > PROTECTED]> wrote:
> > > > >>>>>>> Hello,
> > > > >>>>>>>
> > > > >>>>>>> how do I cancel or delete a Xenomai POSIX thread running in
> > primary
> > > > >>>>>>> context from a higher priority thread? IIUC, pthread_kill()
> > can only be
> > > > >>>>>>> used in secondary context. I tried pthread_cancel(), but it
> > only works
> > > > >>>>>>> when hitting a cancelation point, e.g. pthread_testcancel().
> > Setting
> > > > >>>>>>> pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS) did not
> > help. Is
> > > > >>>>>>> there a code snippet or even an example program showing how
> > to cancel a
> > > > >>>>>>> pthread in primary context?
> > > > >>>>>> pthread_kill or pthread_cancel should result in sending a
> > signal to
> > > > >>>>>> the target thread, so should cause this thread to switch to
> > secondary
> > > > >>>>>> mode to handle it. If you want to wait for the target thread
> > to be
> > > > >>>>>> canceled, you should use pthread_cancel and pthread_join.
> > > > >>>>> There is no way to cancel a pthread in primary mode from
> > another pthread?
> > > > >>>> No. You always need secondary mode to effectively delete a
> > thread. The
> > > > >>>> same goes for the native skin.
> > > > >>> Ok. I understand what you mean. You want pthread_cancel not to
> > leave
> > > > >>> primary mode. This can easily be done by causing pthread_cancel
> > to use
> > > > >>> the kernel-space real-time pthread_cancel service. This should
> > work
> > > > >>> with no further modification.
> > > > >> I want to cancel/delete a task running in primary mode, e.g.
> > > > >>
> > > > >> void* work_task(void* dummy)
> > > > >> {
> > > > >> int count = 0;
> > > > >> while (1)
> > > > >> count++;
> > > > >> }
> > > > >>
> > > > >> from the outside (= another higher priority task). How can I use
> > the
> > > > >> kernel-space real-time pthread_cancel service? My POSIX app is
> > runs in
> > > > >> user-land.
> > > > >
> > > > > I was thinking about adding a pthread_cancel syscall that would
> > have
> > > > > triggered the kernel-space pthread_cancel. But this will not work:
> > > > > user-space cleanup handlers would no longer get executed. However,
> > > > > this can work for pthread_kill. Here is a patch which adds the
> > > > > pthread_kill syscall.
> > > >
> > > > Great, thanks a lot. This seems to work but I'm now fiddling with
> > proper
> > > > cleanup and exit. I have attached my small test program. It behaves
> > > > somehow strange, at least to me:
> > > >
> > > > - I see task period overruns when the low prio task is started. I
> > > > suspect some switch to secondary mode in init_task().
> > > >
> > > > - The program/system hangs after the listed messages:
> > > >
> > > > # ./kill_pthread
> > > > Starting high_prio_task
> > > > Killed low_prio task: count=3813129, overruns=0
> > > >
> > > > Any idea what I'm doing wrong?
> > > >
> > > > This is with Linux 2.4.25 and Xenomai 2.3.x on a MPC5200 board.
> > >
> > > Your test runs fine with Xenomai trunk (on ARM). I will now try with
> > > current state of the v2.3.x branch.
> >
> > Works with v2.3.x too.
>
> I re-activated my test PC running Linux 2.6.20.21. with Xenomai 2.3.x.
> There the program runs fine _without_ your pthread_kill patch. For some
> reason the low_prio_task() is running in secondary mode (do you know
> why? Is there a function to check the mode?). I added
>
> struct sched_param param = { .sched_priority = LOW_PRIO };
> pthread_setschedparam(pthread_self(), SCHED_FIFO, ¶m);
>
> to the head of that function and then I get:
>
> ./kill_pthread
> Starting high_prio_task
> BUG: NMI Watchdog detected LOCKUP
> Killed low_prio task: count=1588495996, overruns=0
> Exiting main
>
> I have attached the corresponding oops in case it's of interest.
> Unfortunately, with your patch and adding the function
> __real_pthread_kill() to wrappers.c, the behavior is the same. I'm going
> to repeat the tests with Xenomai trunk tomorrow.
The oops is due to the NMI watchdog calling some linux domain functions
over Xenomai domain. You should probably use Xenomai watchdog instead.
As for the reason why the watchdog triggers: are you sure you are
running the kernel recompiled after having applied the patch?
--
Gilles Chanteperdrix.
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